Mixing involves manipulating a heterogeneous system to obtain a more homogenous system. Agitation is one of the means by which mixing can be accomplished. Mixing may result in change of heat and mass transfer. The equipment used for processes of mixing multiple liquids or solids make use of tanks/containers/flasks. The mixing process exerts certain amount of shear force on the matter being mixed.
Equipment used for mixing is referred to as mixers. The mixers differ in their construction based on the desired output and the limitations to be adhered to in obtaining the output. A mixer can generally disperse one phase (liquid, solid, gas) into a main continuous phase. A rotor or impellor, together with a stationary component known as a stator, is used either in a tank containing the solution to be mixed, or in a pipe through which the solution passes. The use of impellor or rotor creates shear force and thus acts as enabler for homogenization of two dissimilar materials. For example a high-shear mixer can be used to create emulsions, suspensions, lyosols (gas dispersed in liquid), and granular products. It is used in the adhesives, chemical, pharmaceutical, and plastics industries for emulsification, homogenization, particle size reduction, and dispersion.
Alternatively, a mixer can be provided with a stirrer connected to a motor to drive the stirrer for agitating the substances at required speeds. The stirrer could comprise a plurality of blades and is rotated in clock wise or anti clock wise direction using the motor for mixing liquid or solids. In conventional method the liquids of different densities are mixed by moving the liquids from top to bottom and vice versa thus the pattern of mixing the liquids is limited to only one pattern due to stirrer possessing only one degree of motion. In order to obtain uniform mixing, vigorous agitation is induced through high speed stirrers which will cause high turbulence and thus higher velocity of moving particles and shear force on the molecules.
Circulation and shear of the liquid in a vessel can be generated by certain combinations of pressure and vacuum. If mixing is to be done in the absence of pressure and vacuum, then satisfactory combination of vertical and lateral movement can be obtained economically using suitable dimension, proportions, and internal construction of liquid mixing vessels. This needs to be chosen to suit the demands of the application, for example, when liquids of different densities are required to be mixed homogeneously.
Various forms of mixers are also used in the biological lab and biotechnology industries, examples include vortex mixer. It consists of an electric motor with the drive shaft oriented vertically and attached to a cupped rubber piece mounted slightly off-center. As the motor runs the rubber piece oscillates rapidly in a circular motion. When a test tube or other appropriate container is pressed into the rubber cup and the motion is transmitted to the liquid inside and a vortex is created.
A magnetic stirrer or magnetic mixer is another example of a laboratory device that employs a rotating magnetic field to cause a stir bar immersed in a liquid to spin very quickly, thus stirring it. The rotating field may be created either by a rotating magnet or a set of stationary electromagnets, placed beneath the vessel with the liquid. Magnetic stirrers often include a hot plate or some other means for heating the liquid. Other such examples include homogenizers, orbital shakers etc.
Current mixers in the prior art are found to produce high velocity, turbulence, shear stress and frothing. All these factors can be damaging to biochemical/biological components and are therefore undesirable in biotechnology and biomedical industries. For example, several biochemical components such as proteins can get oxidized or denatured by frothing. Turbulence can be especially disadvantageous while mixing living biological samples such as cells and tissues which can be damaged by effect of shear force. Currently shear and turbulence effects can be reduced by using exogenous additives such as a mild surfactant. In biological samples use of such additives can be toxic and undesirable.
In light of the foregoing discussion, it is necessary to provide an improved system for efficient mixing. Present disclosure relates to a multi-purpose system for mixing at least two identical or different phases without any turbulence or frothing and can further also perform the functions of phase separation, sedimentation and dispersion as and when required after the mixing process.